From Detroit. Have 3 pistols. Anyone have advice on how to proceed so as to not be arrested.

Hopefully, none qualify as assault weapons under CA law, because if they do you may not bring them in.  If they do, reconfigure them so they don't.

Do not bring magazines that hold over ten rounds.

You have 30 days to notify the CA Department of Justice of the handguns you've brought into the State.

You should read this whole thing but I provided an excerpt below.



Assault Weapon Definition for Handguns -

1.  A semiautomatic pistol that does not have a fixed magazine but has any one of the following:

   a)  A threaded barrel, capable of accepting a flash suppressor, forward handgrip, or silencer.
   b)  A second handgrip.
   c)  A shroud that is attached to, or partially or completely encircles, the barrel that allows the bearer to fire the weapon without burning the bearer's hand, except a slide that encloses the barrel.
   d)  The capacity to accept a detachable magazine at some location outside of the pistol grip.

2.  A semiautomatic pistol with a fixed magazine that has the capacity to accept more than 10 rounds.

If not locked in to Calabasas, consider Ventura County, a little farther west.  Much 2A friendlier, CCW friendlier, too.